Memory loss (amnesia) is unusual forgetfulness. It may refer to not being able to remember new events, not being able to recall one or more memories of the past, or both.

Forgetfulness; Amnesia; Impaired memory; Loss of memory; Amnestic syndrome

The cause determines whether amnesia comes on slowly or suddenly, and whether it is temporary or permanent.

Normal aging may lead to trouble learning new material or requiring a longer time to remember learned material. However, it does not lead to dramatic memory loss unless diseases are involved.

Memory loss can be seen with impaired concentration, such as with depression. It can be hard to tell the difference.

There are many areas of the brain that help you create and retrieve memories. Damage or malfunction of any of these areas can lead to memory loss.

Memory loss due to problems with specific brain areas may be different. It may involve only memory of recent or new events, passed or remote events, or both. the amnesia may be only for specific events or for all events. The problem may involve learning new information or forming new memories.

Mental or thinking abilities may still be present or may have been lost. Filling in the details with imagined events (confabulation), and disorientation to time and place may occur.

Memory loss may be for words and thoughts only, or for motor memory (the body can no longer perform specific actions). Memory loss may also be partial, meaning failing to remember only a selected group of items.

Memory loss may be short-term (called transient).

Causes of memory loss include:

• Alcohol or ilicit drug intoxication
• An event in which not enough oxygen was going to the brain (heart stopped, stopped breathing, complications from receiving anesthesia)
• Brain growths (caused by tumors or infection)
• Brain infections such as Lyme disease, syphilis, or HIV/AIDS
• Brain surgery , such as surgery to treat seizure disorders
• Cancer treatments, such as brain radiation, bone marrow transplant, or after chemotherapy
• Certain medications
• Certain types ofseizures
• Dementia
• Depression, bipolar disorder, or schizophrenia when symptoms have not been well controlled
• Dissociative disorder (not being able to remember a major, traumatic event; the memory loss may be short-term or long-term)
• Drugs such as barbiturates or benzodiazepines
• Electroconvulsive therapy (especially if it is long-term)
• Encephalitis of any type (infection, autoimmune disease, chemical/drug induced)
• Epilepsy that is not well controlled with medications
• Head trauma or injury
• Heart bypass surgery
• Illness that results in the loss of, or damage to nerve cells (neurodegenerative illness), such as Parkinson's disease, Huntington's disease, or multiple sclerosis
• Long-term alcohol abuse
• Migraine headache
• Mild head injury or concussion
• Nutritional problems (vitamin deficiencies such as low vitamin B12)
• Permanent damage or injuries to the brain
• Transient global amnesia
• Transient ischemic attack (TIA)

Images

Central nervous system

Review Date: 03/22/2010
Reviewed By: Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)